Temperature dependences of the reactions of O(3P) atoms with selected chloroethenes between 298 and 359 K

M.TERUEL, P. COMETTO, R.TACCONE AND S.LANE

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS

Wiley Interscience

Lugar: USA; Año: 2005 vol. 37 p. 763 - 769

0538-8066

The rate constants for the gas-phase reactions of ground state oxygen atoms with  CF2=CFCl (1) , (E/Z)-CFCl=CFCl (2), CFCl=CH2 (3) and (E/Z)-CFH=CHCl (4) have been measured directly using a discharge flow tube coupled to a chemiluminescence detection system. The experiments were carried out under pseudo-first-order conditions with  [O(3P)]0 << [ethene]0. The temperature dependences of the reactions were studied for the first time in the range 298-359 K. The proposed Arrhenius expressions ( units of cm3 molecule-1 s-1) were: k1 = (1.07 ± 0.32) x 10-11 exp{-(8000 ± 1600)/RT}, k2 = (0.56 ± 0.10) x 10-11exp{-(8700 ± 500)/RT}, k3 = (4.23 ± 1.25) x 10-11 exp{-(12700 ± 800)/RT}, k4 = (1.13 ± 0.62) x 10-11 exp{-(10500 ± 1500)/RT}. All the rate coefficients display a positive temperature dependence, which highlights the importance of the irreversibility  of the addition mechanism for these reactions. Halogen substitution in the ethene is discussed in terms of reactivity with O(3P).